Consecutive Numbers

Consecutive means following one after another, in order. Hence, consecutive numbers are the numbers that follow one another successively. For example, 1, 2, 3, 4, 5, 6, and so on. In mathematics, consecutive numbers follow each other in ascending order. To understand consecutive numbers fully, we should first learn the concept of successor and predecessor.

 

Successor:
Successor is something that comes next. For example, 2 comes after 1, so 2 is the successor of 1. In the same way, 3 follows 2, making 3 the successor of 2.


Predecessor:
The predecessor is the opposite of the successor. It is something that comes before the current object or number. For example, 1 precedes 2, so 1 is the predecessor of 2. Similarly, 2 is the predecessor of 3 because 2 comes before 3.
 

There are four main types of consecutive numbers. They are as follows:


Natural Consecutive Numbers:
Natural numbers are positive numbers starting from 1. These numbers are used only for counting objects.


Consecutive Even Numbers: 
Even numbers are divided evenly by 2. So the common difference between consecutive even numbers is 2. For instance, 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 are the consecutive even numbers from 1 to 20.


Consecutive Odd Numbers:
Odd numbers are those numbers that cannot be divided by 2. The odd consecutive numbers also have a difference of 2 between each number. For example, the odd consecutive numbers from 1 to 20 are: 1, 3, 5, 7, 9, 11, 13, 15, 17, 19.


Consecutive Integers:
Consecutive integers are those integers that appear continuously without any gaps. E.g., +1, +2, +3, and so on, or -1, -2, -3, -4, -5, etc., are consecutive integers.     
 

There are various properties of consecutive numbers. Some of them are mentioned below:
 

• Consecutive numbers have a fixed difference. Any two odd or even consecutive numbers will have a difference of 2. Otherwise, consecutive numbers will have a difference of 1.
   
• If two odd consecutive numbers are added, the sum will result in an even number. If two even consecutive numbers are added, the sum would result in an even number.
   
• If there is a sequence of odd numbers ‘n,’ their sum will always be divisible by the total number ‘n.’ For example, let’s say 1, 3, 5, and 7 are a sequence of odd numbers where ‘n’ is 4 (total count of numbers). Now, let’s add the numbers and divide the sum by 4.
  (1 + 3 + 5 + 7)/4 = 16/4 = 4. Hence, the property is proved.
   
• The HCF of two consecutive numbers is always 1.
   

We can use formulas to work efficiently with consecutive numbers. Depending on the type of consecutive numbers, different formulas will be used. Take a look at the following scenarios and see how different formulas are used for different purposes: 


Consecutive Even Number Formula: 
If 2a is an even number, then the next even number can be found by adding consecutive even numbers to 2a. Therefore, the formula to find consecutive even numbers is: 2a, 2a + 2, 2a + 4…


Consecutive Odd Number Formula: 
We use 2a + 1 to represent odd numbers. So the next odd numbers can be found by adding consecutive odd numbers to 2a. Hence, the formula is:
2a + 1, 2a + 3, 2a + 5…


Natural Consecutive Number Formula:
If ‘a' is an integer, then the next consecutive numbers can be found by using the formula: a, a + 1, a + 2, and so on.


Sum of Consecutive Even Numbers:
We use the formula S = n(n + 1) to find the sum of consecutive even numbers.
For example, to find the sum of the first 3 even numbers, we can substitute the values in the formula given above. So, S = 3(3 + 1) = 12. Twelve is the sum of the first three even numbers.


Sum of Consecutive Odd Numbers:
The highest common factor, or HCF, between two consecutive numbers is always 1.
For example, n can be replaced by 6 to find the sum of the first 6 consecutive odd numbers. Using the formula, we can write n2 = 62 = 36. So the sum of the first 6 consecutive odd numbers is 36.
 

Two consecutive integers are co-prime with HCF 1 because 1 is the only common factor between two numbers that are consecutive. For instance, 45, 46 is a sequence of two consecutive numbers. The only common factor 45 and 46 in this series is 1. Therefore, the HCF of 45 and 46 is 1.
 

The consecutive numbers have numerous applications across various fields. Let’s explore how consecutive numbers are used in different areas:
 

• Arranging Seats in Auditoriums and Theaters:Consecutive numbers are mostly used in arranging seats in theaters, stadiums, and auditoriums. All these seats are marked in order for proper arrangement and identification.
   
• House and Apartment Numbering: 
  Buildings and houses in a street are often numbered in consecutive order to maintain a proper layout. Even-numbered houses are on one side, while odd-numbered houses are on the other. This arrangement makes it easy for postal services and visitors to locate addresses efficiently.
   
• Time and Scheduling: Consecutive numbers play an important role in organizing daily activities, calendars, and event timings. Days of the week follow a consecutive pattern, and school periods or work shifts are numbered consecutively. This arrangement helps in planning and time management.